What is the replacement for Hibernate's Transaction.wasCommitted method?

You seem to be looking for session.getTransaction().getStatus(). For example,

session.getTransaction().getStatus() == TransactionStatus.COMMITTED
session.getTransaction().getStatus() == TransactionStatus.ROLLED_BACK

You may also want to examine the docs of TransactionStatus to see the relatively fine granularity of transaction statuses, as you might either want or need more inclusive substitutes than those above. Also, don't overlook TransactionStatus's methods, which you may find helpful. For example,

session.getTransaction().getStatus().isOneOf(
        TransactionStatus.MARKED_ROLLBACK,
        TransactionStatus.ROLLING_BACK,
        TransactionStatus.ROLLED_BACK)